Every business owner who has ever filed a tax return has wondered, at some level, how Revenue decides who to look at. The answer is more systematic and more data-driven than most people realise. Revenue’s compliance programme is risk-based, which means the probability of your business being selected for audit is not random - it is driven by a range of factors that can be understood, and in many cases managed.
Understanding what attracts Revenue’s attention is not about gaming the system. It is about understanding what genuine compliance looks like from Revenue’s perspective - and ensuring that your returns accurately reflect your business.
Revenue’s Risk Profiling System
Revenue operates an integrated risk analysis system that ingests data from multiple sources and produces a risk score for each registered taxpayer. Businesses and individuals above certain risk thresholds are selected for compliance intervention. Those below the threshold are left alone.
The risk score is not a single metric - it is a composite assessment of a range of signals. Here is how that assessment works in practice.
The Main Risk Triggers
Statistical outliers against industry benchmarks. Revenue holds detailed data on financial ratios - gross margin, expense ratios, staff costs as a percentage of turnover, net profit margins - across every industry sector. If your returns show ratios that are significantly out of line with your sector averages, that discrepancy is a red flag.
A plumbing business with a gross margin of 15% when the sector average is 45% will attract scrutiny. A consultancy declaring very low profits relative to its turnover will be flagged. A construction company with unusually high materials costs relative to labour will be noted.
This does not mean your numbers have to match the industry average - legitimate variation exists. But if your numbers diverge significantly, you should be able to explain why.
Cross-referencing across tax heads. Revenue does not look at your income tax return in isolation. It cross-references your income tax or corporation tax return against your VAT returns, your PAYE returns, and your RCT records. Inconsistencies between these returns are a significant trigger.
For example: if your VAT returns show turnover of 400,000 euro but your income tax return shows turnover of 350,000 euro, Revenue will want to understand the 50,000 euro gap. There may be a perfectly legitimate explanation - timing differences, exempt supplies, intra-group transactions - but the discrepancy will be flagged and examined.
Unexplained changes between years. A significant and unexplained change in a key financial metric from one year to the next attracts attention. Turnover that drops 40% without an obvious explanation, expenses that double, or a previously profitable business that suddenly declares a loss are all flagging events.
Third-party data mismatches. Revenue receives data from a wide range of third parties:
Banks - all cash lodgements and payments above certain thresholds. Property registration - sales, purchases, and rental transactions. Companies Registration Office - company filings and director data. Other government departments - Social Protection, Local Government. EU information exchange - DAC8 (crypto), CRS (foreign financial accounts), FATCA (US-linked accounts). Land Registry - property ownership and transactions. Crypto exchanges - transaction data under DAC8.
If any of this data shows income or transactions not reflected in your returns, the mismatch is flagged. The more data Revenue receives - and it is receiving more every year - the more visible undeclared income becomes.
Cash-intensive sectors. Certain sectors attract disproportionate Revenue attention simply because they are historically associated with higher rates of non-compliance. Cash-intensive businesses - retail, hospitality, construction, market traders, hairdressers and beauty businesses - are subject to greater scrutiny than businesses operating entirely through electronic transactions.
This is not an accusation that all cash businesses are non-compliant. It is a recognition that cash creates opportunities for non-declaration that electronic transactions do not, and Revenue’s resource allocation reflects the risk accordingly.
Lifestyle versus declared income mismatches. Revenue’s risk assessment includes a lifestyle analysis component - looking for indicators of spending that are inconsistent with declared income. Expensive car registrations, property purchases, foreign holidays, and other lifestyle signals that cannot be supported by the declared income level are flagging events. This is more prominent at the individual level than at the business level, but director/shareholder lifestyle can affect business audit risk.
Late or non-filing. Not filing returns on time is itself a risk trigger. Taxpayers who consistently file late, file amended returns, or have a history of underpayment are at higher risk of selection. This is distinct from the late filing penalties - it means that the compliance history itself affects your future audit risk profile.
Agent risk. Revenue’s risk system also considers the compliance record of your tax agent - your accountant. An agent with a history of filing inaccurate returns, being involved in tax avoidance schemes, or representing clients with poor compliance records is a risk factor for all that agent’s clients. This is a good reason to ensure your accountant has a clean compliance record.
The Random Element
Alongside the risk-based selection, Revenue conducts a proportion of audits on a random basis - businesses with no specific risk flag that are selected to maintain a general compliance deterrent and to gather data. The exact proportion is not published, but it is generally accepted to be a minority of total audits.
For most businesses, the probability of random selection in any given year is low. But it is not zero, and it applies regardless of compliance quality.
What Genuinely Reduces Audit Risk
Complete, accurate, and timely filing. Returns filed on time, every time, with consistent figures across all tax heads, is the single most effective risk reduction measure. Consistency - figures that reconcile between VAT, PAYE, and income/corporation tax returns - removes the cross-head discrepancy triggers.
Records that support your returns. Revenue audit risk is not just about being selected - it is about what happens when you are. Businesses with complete, organised records that support every line of every return consistently achieve better outcomes in audit. The practical risk reduction from good record-keeping operates at both the selection stage (compliant businesses with consistent records are lower risk) and the audit stage (they have evidence to support their positions).
Explainable deviations from sector norms. If your figures diverge from industry averages for legitimate reasons - you operate a different business model, you have unusually high or low costs for specific reasons - document those reasons. An explanatory note in the accounts, or a record maintained by your accountant explaining the variance, reduces the unexplained-outlier risk.
Proactive engagement on errors. If you discover an error in a filed return - you miscalculated a capital gain, omitted a rental income figure, claimed an expense you later realised was personal - correct it as soon as possible through a voluntary disclosure or amended return. An error that is corrected proactively is a much smaller problem than one discovered during an audit.
The Bottom Line on Risk
The honest answer to “how does Revenue decide who to audit” is: they look for businesses where the data suggests there might be something worth examining. The best protection against audit selection is filing complete, accurate, timely returns that are consistent with the underlying reality of your business.
If your returns are accurate and your records are in order, a Revenue audit is an inconvenience rather than a catastrophe. If they are not, Revenue’s increasing data capabilities mean the question is not whether they will find it - it is when.
Paddy Malone FCA AITI
Paddy is the principal of Malone & Co. Chartered Accountants in Dundalk. A Fellow of Chartered Accountants Ireland and a Chartered Tax Consultant with the Irish Tax Institute, he has been advising businesses across County Louth and the North-East for over 35 years.